Cavity Wall Insulation Cost Calculator — UK Prices 2025
Cavity Wall Insulation Cost Calculator
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How much does cavity wall insulation cost in the UK?
Use our calculator above to get an accurate estimate based on your specific requirements. Prices are based on real quotes from UK tradespeople and updated quarterly.
What affects the cost of cavity wall insulation?
- Location: London and the South East are 15–40% more expensive than the national average.
- Size and complexity: Larger or more complex jobs cost proportionally more.
- Material quality: Budget, mid-range and premium specifications can vary by 2–3x.
- Time of year: Demand peaks in spring and summer — book in winter for better availability and pricing.
- Access: Difficult access (scaffolding, confined spaces) adds to labour costs.
How to save money on cavity wall insulation
- Get at least 3 quotes from different tradespeople.
- Book during quieter periods (January–March for most trades).
- Be flexible on start dates — tradespeople often discount for convenient scheduling.
- Supply your own materials where possible (but confirm with your tradesperson first).
- Combine jobs — having multiple trades on site at once can reduce overall costs.
How to find a good tradesperson
Always check reviews on Checkatrade, Rated People or MyBuilder. Ask for references from recent similar jobs. Ensure they are appropriately qualified and insured. Never pay the full amount upfront — a deposit of 10–25% is standard.
Frequently asked questions
How much does cavity wall insulation cost in the UK?
Cavity wall insulation costs £400–£1,200 for a typical semi-detached house. Under ECO4 or the Great British Insulation Scheme, it may be free for eligible households.
How much can I save with cavity wall insulation?
Cavity wall insulation saves £200–£400/year on heating bills for a typical semi-detached house. The payback period is typically 2–5 years at full cost, or immediate if installed free under ECO4.
Is my home suitable for cavity wall insulation?
Most UK homes built between 1920 and 1990 have cavity walls. Homes built before 1920 usually have solid walls. You can check by looking at the brick pattern — stretcher bond (all bricks lengthways) indicates a cavity wall.
What is the ECO4 scheme?
ECO4 (Energy Company Obligation 4) provides free energy efficiency improvements including cavity wall insulation to households on certain benefits or with low EPC ratings. Apply through your energy supplier or a registered ECO4 installer.
Can cavity wall insulation cause damp?
Poorly installed cavity wall insulation can cause damp by bridging the cavity. Always use a registered installer (CIGA-approved) and ensure the cavity is suitable (no existing damp, minimum 50mm cavity width).